<Session>.options_get(options.HOST) raises exception

[Jo5ta]

Running the following code snippet raises an exception:

from ssh.session import Session
from ssh import options
HOST = 'localhost'
s = Session()
assert s.options_set(options.HOST, HOST) == 0
assert s.options_parse_config("~/.ssh/config") == 0
print(s.options_get(options.HOST) == 0)

$ ssh-python/examples/exec.py
[2024/11/08 09:45:07.728363, 1] ssh_options_get:  Invalid argument in ssh_options_get
Traceback (most recent call last):
  File "ssh-python/examples/exec.py", line 20, in <module>
    print(s.options_get(options.HOST) == 0)
  File "ssh/session.pyx", line 341, in ssh.session.Session.options_get
    raise OptionError
ssh.exceptions.OptionError

The installed version is:

$ pip list | grep ssh-python
ssh-python          1.0.0

This should work because HOST option is a string and should therefore be usable as arg.
Tested with: ssh-python version 1.0.0

Analysis

Function definition

    def options_get(self, Option option):
        """Get option value. This function can only be used for string options.
        For numeric or other options use the individual functions.
        """
        cdef char *_value
        cdef char **value = NULL
        cdef int rc
        cdef bytes b_value
        with nogil:
            rc = c_ssh.ssh_options_get(
                self._session, option._option, value)
        if rc < 0:
            raise OptionError
        _value = value[0]
        b_value = _value
        c_ssh.ssh_string_free_char(_value)
        return to_str(b_value)

The exception is therefore thrown because the rc was less than 0.

Testing the underlying c code does not showed any problem. As the following code snippet executes without a problem for libssh found via cmake with libssh version 0.9.6. Where SSH_OK is equal to 0.

    char *host_option;
    assert(ssh_options_get(session, SSH_OPTIONS_HOST, (char **)&host_option) == SSH_OK);

The installed libs are:

$ apt list | grep libssh-
libssh-4/jammy-updates,jammy-security,now 0.9.6-2ubuntu0.22.04.3 amd64 [installed,automatic]
libssh-dev/jammy-updates,jammy-security,now 0.9.6-2ubuntu0.22.04.3 amd64 [installed]
libssh-doc/jammy-updates,jammy-security 0.9.6-2ubuntu0.22.04.3 all
libssh-gcrypt-4/jammy-updates,jammy-security 0.9.6-2ubuntu0.22.04.3 amd64
libssh-gcrypt-dev/jammy-updates,jammy-security 0.9.6-2ubuntu0.22.04.3 amd64

looking deeper into the repository in found the definition of ssh_option_get which supports SSH_OPTIONS_HOST as a valid argument.

Also there are unittests for the libssh and especially for ssh_option_get in torture_options_get_host. But all of them are passing:

$ ./build/tests/unittests/torture_options
[==========] Running 24 test(s).
[ RUN      ] torture_options_set_host
[       OK ] torture_options_set_host
[ RUN      ] torture_options_get_host
[       OK ] torture_options_get_host
[ RUN      ] torture_options_set_port
[       OK ] torture_options_set_port
[ RUN      ] torture_options_get_port
[       OK ] torture_options_get_port
[ RUN      ] torture_options_set_fd
[       OK ] torture_options_set_fd
[ RUN      ] torture_options_set_user
[       OK ] torture_options_set_user
[ RUN      ] torture_options_get_user
[       OK ] torture_options_get_user
[ RUN      ] torture_options_set_identity
[       OK ] torture_options_set_identity
[ RUN      ] torture_options_get_identity
[       OK ] torture_options_get_identity
[ RUN      ] torture_options_set_global_knownhosts
[       OK ] torture_options_set_global_knownhosts
[ RUN      ] torture_options_get_global_knownhosts
[       OK ] torture_options_get_global_knownhosts
[ RUN      ] torture_options_set_knownhosts
[       OK ] torture_options_set_knownhosts
[ RUN      ] torture_options_get_knownhosts
[       OK ] torture_options_get_knownhosts
[ RUN      ] torture_options_proxycommand
[       OK ] torture_options_proxycommand
[ RUN      ] torture_options_set_ciphers
[       OK ] torture_options_set_ciphers
[ RUN      ] torture_options_set_key_exchange
[       OK ] torture_options_set_key_exchange
[ RUN      ] torture_options_set_hostkey
[       OK ] torture_options_set_hostkey
[ RUN      ] torture_options_set_pubkey_accepted_types
[       OK ] torture_options_set_pubkey_accepted_types
[ RUN      ] torture_options_set_macs
[       OK ] torture_options_set_macs
[ RUN      ] torture_options_copy
[       OK ] torture_options_copy
[ RUN      ] torture_options_config_host
[       OK ] torture_options_config_host
[ RUN      ] torture_options_config_match
[       OK ] torture_options_config_match
[ RUN      ] torture_options_config_match_multi
[       OK ] torture_options_config_match_multi
[ RUN      ] torture_options_getopt
[       OK ] torture_options_getopt
[==========] 24 test(s) run.
[  PASSED  ] 24 test(s).
[==========] Running 17 test(s).
[ RUN      ] torture_bind_options_import_key
Changed directory to: temp_dir_6m8feI
[       OK ] torture_bind_options_import_key
[ RUN      ] torture_bind_options_hostkey
Changed directory to: temp_dir_zOa06C
[       OK ] torture_bind_options_hostkey
[ RUN      ] torture_bind_options_bindaddr
Changed directory to: temp_dir_P9JiyE
[       OK ] torture_bind_options_bindaddr
[ RUN      ] torture_bind_options_bindport
Changed directory to: temp_dir_rVKRtu
[       OK ] torture_bind_options_bindport
[ RUN      ] torture_bind_options_bindport_str
Changed directory to: temp_dir_LBM3Ng
[       OK ] torture_bind_options_bindport_str
[ RUN      ] torture_bind_options_log_verbosity
Changed directory to: temp_dir_KY2Gn4
[       OK ] torture_bind_options_log_verbosity
[ RUN      ] torture_bind_options_log_verbosity_str
Changed directory to: temp_dir_3abnsb
[       OK ] torture_bind_options_log_verbosity_str
[ RUN      ] torture_bind_options_rsakey
Changed directory to: temp_dir_i4JMEP
[       OK ] torture_bind_options_rsakey
[ RUN      ] torture_bind_options_ecdsakey
Changed directory to: temp_dir_vCiinR
[       OK ] torture_bind_options_ecdsakey
[ RUN      ] torture_bind_options_banner
Changed directory to: temp_dir_MhjchD
[       OK ] torture_bind_options_banner
[ RUN      ] torture_bind_options_set_ciphers
Changed directory to: temp_dir_h8cvKn
[       OK ] torture_bind_options_set_ciphers
[ RUN      ] torture_bind_options_set_key_exchange
Changed directory to: temp_dir_NC2lFF
[       OK ] torture_bind_options_set_key_exchange
[ RUN      ] torture_bind_options_set_macs
Changed directory to: temp_dir_667NhP
[       OK ] torture_bind_options_set_macs
[ RUN      ] torture_bind_options_parse_config
Changed directory to: temp_dir_veocnN
[       OK ] torture_bind_options_parse_config
[ RUN      ] torture_bind_options_config_dir
Changed directory to: temp_dir_t03DKj
[       OK ] torture_bind_options_config_dir
[ RUN      ] torture_bind_options_set_pubkey_accepted_key_types
Changed directory to: temp_dir_X6HGwg
[       OK ] torture_bind_options_set_pubkey_accepted_key_types
[ RUN      ] torture_bind_options_set_hostkey_algorithms
Changed directory to: temp_dir_SmofOs
[       OK ] torture_bind_options_set_hostkey_algorithms
[==========] 17 test(s) run.
[  PASSED  ] 17 test(s).

Unfortunately, I have no experience with c bindings in python and therefore cannot analyse the problem any further.

[pkittenis]

Sounds like the provided config does not set host, there for it cannot be retrieved.